Study On Weak Signal Detection Approaches Based On Coupling Chaotic Oscillators

Weak signal detection technology is one of the important contents in the area of the modern information processing, it has made some progress in some areas, but it is still a difficult breakthrough problem in engineering practice. It has been widely used in many fields: communications, radar, physics, biomedical, rotating machinery fault diagnosis and so on. Under the strong noise background, it will fail for the general traditional linear filtering method. With the development of science and technology, the method of chaos theory and signal processing combination makes the weak signal detection technology have a leapfrog development. Chaotic systems make use of the sensitivity dependence on initial conditions and the immunity for noise to achieve detection of weak periodic signal, thus reducing the SNR threshold of signal detection, improving the precision of weak signal detection. This article takes advantage of the superiority of chaotic systems to achieve fault detection of weak signals.Thesis presents the nature and the definition of chaos, characteristics and the principle and method of the chaos judgment, expounding a simple analysis of several common chaotic models: Duffing oscillator system, Van der pol oscillator system, Lorenz chaotic system and Logistic system model, it provides a theoretical basis.Secondly, it presents as for that the traditional method of detection in low SNR is not ideal, so the Duffing oscillator and Van der pol oscillator two different chaotic oscillators are coupled, establishing the nonlinear coupling system model, carring out the dynamic behavior analysis, showing better stability and accuracy than traditional weak signal detection, finally through the time scale transformation equations to adapt for signals of different frequencies so as to achieve the detection of any unknown frequency of the periodic signal, studying weak signal detection under the background of color noise. Thirdly, it presents two identical Duffing oscillator are coupled to synchronize to establish coupling system to detect weak periodic signal, comparing with the conventional single Duffing oscillator system, it is the more robust, then we conduct the weak pulse signal and achieve good results. Finally, it is early bearing fault diagnosis experimental designation, Through the acquisited fault signal is input to the two coupling Duffing oscillator system to carry out the experimental verification, this system can detect weak fault signal and achieve good results. Chaos system will have good prospects for development in early fault diagnosis.